This invention relates to water meters and, more particularly, to water meters having a rotatable body (such as a propeller mounted on spindle) which turns in proportion to the volume of water that is measured, and to means for electronically totalizing the number of rotations of the body to give a preferably digital readout.
A conventional water meter has a propeller or turbine in a path, such as in a conduit or pipe, which the water follows for example. Several conversion or reduction gear trains transmit the rotations of the propeller to a plurality of pointers, hands, indicators, or registers to show predetermined volume units of a measure, which indicates the volume of the water used.
Such conventional water meters have long been used and are usually characterized by a simple mechanical structure. However, the conventional water meter is deficient, mainly in three points. First, the rotation of the gears and movement of other parts are gradually and adversely affected by wear, during long use of the meter. There is an accumulation thereon of a mineral buildup that is usually called "scale." Second, it is impossible to measure a weak current or low-volume flow of water because the torque given thereby is insufficient to drive the gears. Although, attempts have been made to reduce the driving torque to a minimum, it cannot be reduced beyond a certain limit if gears are used. Third, a strong water flow reduces the serviceable life of the meter because the gears are too heavily loaded, and that introduces excessive wear on the bearings.
In addition, different sets of conversion gear trains have to be prepared for different diameter conduits and for different units of measure. Inasmuch as there are relatively few teeth on each of the gears, an error of about 0.5% is inevitable, with flow-to-readout conversion by mechanical gears.